And now, in a newly released recording of an interview she gave to Pinellas sheriff's investigators, Stewart explains how the secret began to unravel, and how Temple came to be charged with the murder of his wife, Rosemary Christensen, whose body would later be found in that grave.

It began in August 1999, Stewart said, when she and Temple were having a rambling and disjointed conversation in his condo. Though married and in his late 40s, Temple had a relationship with the 22-year-old Stewart. And during this conversation, Stewart eventually saw that Christensen was dead, her body at the foot of the bed.

Stewart said Temple told her Christensen, a real estate agent originally from Australia, had died by falling on a knife, detectives said. Stewart told them that Temple persuaded her to help him dispose of the body.

They went to Wal-Mart and bought a huge plastic storage container with wheels on it, Stewart said in the statement. They traveled to property her father owns in rural Gilchrist County in North Florida.

Temple dug a 6-foot-deep grave, she said. The body was covered in garbage bags and wedged into the plastic container. As she held a flashlight, Temple dumped the container into the grave and filled it in.

The two left the state shortly after the killing.

Though investigators suspected Temple from the beginning, Christensen's vanishing became one of the most enduring mysteries in Pinellas County.

But the secret apparently gnawed at Stewart, who said in the recording that she was closely watched and monitored by Temple. One July day, years later, she needed to know more.

"I said, 'You know, I have never asked you this.' " I said, "Did you kill her?' "

Temple shot back: "No, I didn't."

Another time, when the two were living in California, they were having an argument, and Stewart alluded to her suspicion that Temple had killed his wife. She reminded him that she had helped him hide the body.